6
-24
Machine Protection
This section explains functions for protecting the machine.
Limiting Motor Torque (Torque Limit Function)
The motor torque limit function is enabled with flux vector control and open-loop vector control.
In the open-loop vector control and flux vector control, the user-set value is applied to the torque limit by cal-
culating internally the torque output by the motor. Enable this function if you do not want a torque above a
specified amount to be applied to the load, or if you do not want a regeneration value above a specified
amount to occur.
Related Constants
Note The forward torque limit is the limit value when the analog input signal generates forward torque. This torque limit setting is enabled even when the
analog input signal generates forward torque while the motor is operating (regeneration).
* The factory setting will change when the control method is changed.
Setting the Torque Limit in Constants
Using L7-01 to L7-04, you can set individually four torque limits in the following directions: Forward drive,
reverse drive, forward regeneration, and reverse regeneration.
Setting Precautions
•
When the torque limit function is operating, control and compensation of the motor speed is disabled
because torque control is given priority. Therefore, the acceleration and deceleration times may increase or
the number of motor rotations may decrease.
•
The torque limit accuracy is ±5% at the output frequency of 10 Hz or above. When output frequency is less
than 10 Hz, accuracy is lowered.
Constant
Number
Name
Description
Setting
Range
Factory
Setting
Change
during
Opera-
tion
Control
Methods
MEMO-
BUS
Register
Open-
loop
Vector
Flux
Vector
Display
L7-01
Forward drive
torque limit
Sets the torque limit value as a percentage
of the motor rated torque.
Four individual regions can be set.
0 to
300
100%
*
No
A
A
560H
Torq Limit Fwd
L7-02
Reverse drive
torque limit
0 to
300
100%
*
No
A
A
561H
Torq Limit Rev
L7-03
Forward
regenerative
torque limit
0.0 to
100.0
0.5%
*
No
A
A
562H
Torq Lmt Fwd
Rgn
L7-04
Reverse
regenerative
torque limit
0.0 to
100.0
0.5%
*
No
A
A
563H
Torq Lmt Rev
Rgn
Output frequency
Accelerates to
lower limit
Same
frequency
Reference
frequency reset
* The frequency matching signal turns on when the motor
is not accelerating/decelerating while the Run Command is on.
Lower limit
Forward
operation/stop
UP command
DOWN
command
Frequency
matching signal*
Power supply
Upper limit
On
On
On
On
On
On
d4-01=1
d4-01=0
